Ruminants, both domestic and wild, are the primary sources of Q fever, a zoonosis that causes reproductive abnormalities in animals and acute (self-limiting flu-like syndromes) and chronic (pneumonia, hepatitis, and endocarditis) conditions in people. The disease affects people and domestic ruminants globally, with vaccination being the primary method of control and management. Coxevac is the only approved vaccine for preventing Q fever in ruminants. This phase I vaccination greatly decreases the risk of miscarriage and shedding. Vaccination against Q fever has not been shown to be effective in buffalo, despite their extensive farming in several countries. This study used phase-specific ELISAs to assess the humoral response and its impact on abortion rates in buffalo. A total of 35 water buffalo were inoculated with two doses of a commercial vaccine and screened for phase I and II antibodies. Seroreactivity increased significantly between t0 and t1, and decreased somewhat between t1 and t2. Seroconversion did not differ substantially by age or natural infection status. At t1 and t2, naturally pre-infected animals showed somewhat greater reactivity than negative animals, but no significant differences were found. Animals over 20 months demonstrated higher seroreactivity at t1 compared to younger animals, but the difference was not statistically significant. Herd research found that immunization lowered miscarriage and placenta retention rates. The impact of immunization on miscarriage rates was reported regularly. In June, herd research showed 19 placenta retentions and 3 miscarriages due to Coxiella burnetii, which was detected using specialized real-time PCR. After five months after immunization, only five placenta retentions and one miscarriage occurred.
Preliminary evidence suggests that vaccination can be effective in buffalo, even in seropositive animals. However, further research is needed to fully understand the dynamics of seroconversion in this species.